Leg lock for a stand



Dec. 29, 1959 R, E, PETRlCK 2,919,094

LEG LOCK FOR A STAND Filed May 21, 1954 United States Patent O LEG LOCKFOR A STAND Russell E. Petrick, Park Ridge, Ill., assignor to KnoxManufacturing Company, a corporation of Illinois Application May 21,1954, Serial No. 431,392 `3 Claims. (Cl. 248-171) This invention relatesto portable stands for movie picture screens and the like, and moreparticularly to a locking device for releasably -holding the leg membersof such a stand in their folded position.

This application is a continuation-in-part of an application of thisinventor entitled A Portable Stand, filed December 28, 1953, and bearingSerial Number 400,598, now Patent No. 2,886,274.

The primary' object of the present invention is to provide a portablestand having folda'ble leg members and 'bracing links which -aremoi/able between a locked folded position and 'an outwardly spreadposition.

Another object is to provide a portable stand having a spring-urged legunit adapted for limited sliding movement longitudinally of an upright'standard to lock and unlock the leg unit from folded position.

A further object is to provide a portable 'stand in which an end of 'abracing link in folded position is at a slight angle to the uprightstandard so that movement of the leg unit as a whole unlocks the legmembers and also urges the bracing link end and its adjacent leg membertoward outwardly spread position.

' Another object is to provide a leg unit having a latching meansengaging the mid portion of a leg member so that the shock of latchingengagement is reduced.

The invention is illustrated in a preferred embodiment in theaccompanying drawings, in which:

Fig. 1 is a perspective view of the leg unit in spread position;

Fig. 2, van enlarged broken elevational view partly in section showing'a leg member in locked folded position;

Fig. 3, an enlarged broken elevational view partly in section showing aleg member in outwardly spread position;

Fig. 4, a broken top plan view of the leg unit in outwardly spreadposition;

Fig. 5, a broken sectional view taken as indicated on line 5 5 of Fig.3; and

Fig. 6, a broken sectional view taken as 'indicated on line 6-6 of Fig.5.

In the embodiment illustrated, a plurality of leg members 8 are-pivotally secured by rivets 9 to an upper collar 10 mounted forslidable movement longitudinally of the -upright standard '11. The legmembers and the standard are generally made of metal, the leg members 8preferably being channel shaped so that they may lie closely adjacentthe standard when in folded position, and the standard 11 preferablybeing tubular so that it may slidably receive a telescoping extension,not shown. Decorative tips 12 may be provided on each leg member tocover any sharp edges upon the leg ends. A cap 13 is secured to thelower end of the standard 11 by a machine screw or a spot-weld to closethe lower end.

Bracing links 14 are yconnected at one end to each of the leg members 8by rivets 15 and at the other end to a lower collar 16 by rivets 17. Thelower collar '16 is limited in its slidable movement longitudinally ofthe standard 11 'by a pin 18 impaling the lower collar 16 and passingthrough an elong'ated slot 19 in the upright standard 11. As best seenin Fig. 6, the pin 18 also passes through a pair of ears 20 of a-bracket 21 and holds the bracket in position within the tubularstandard "1'1. The lower surface 122 of the bracket 21 and the cap 13confine a compression spring 23 'in the lower end of the standard 11.The spring 23 is slightly compressed so that 'it normally bears upwardlyupon the surface 22 to hold the lower collar 16 in its uppermostposition longitudinally of the standard 11. This position is shown inFig. 6 with the pin 18 at the upper end of the slot 19 in the standard1'1.

The bracing links -14 are joinedV to the leg members 8 and the lowercollar 16 so that the upper end of each link will be positioned at aslight outward angle from the standard 11 when the leg unit is in foldedposition. The 'angle of the folded links 14 is important in unlockingthe legs and moving them to their spread position, as will be more fullyexplained hereafter.

A stationary member, generally designated 24, is fixed upon the standard11 by a rivet or spot-weld. This member may include one or more hookmembers 25 having notches 25a preferably opening downwardly of theupright standard 11. Each of the -hook members 25 is positioned so thatit engages a cooperating latching portion on the leg unit when the legunit is moved to folded position adjacent the standard 11. A fingerpoition 26 is provided on the upper collar 10 to facil'itate movement ofthe upper collar longitudinally of the standard. As the upper 'collar 1h'is vraised by the finger porton 26, the leg members are pivoted towardfolded position approximately parallel to the standard 11, and thebracing links 14, pivoting about the lower collar 13 and the rivets 15,'are recessed within the c'hannels of the leg members 8.

' At least one of the bracing links 114, and preferably -all three ofthem, 'have a narrow lip 27 at one end. The lip 27 is positioned so thatit will snap into the downwardly turned notch 25a of the hook member 25when the leg unit is moved to folded position. As the upper collar 10 ismoved lupwardly on the standard 1'1, the lip 27 first Strikes therounded tip portion 28 of the hook member 25. The tip portion 28 camsthe bracing links '14 'and the lower-collar 16 downwardly against theaction of the compression spring 23. Subsequently the lip 27 rides oifthe rounded tip 28 and snaps into the notch 25a in the lhook portion 25to secure the leg unit in locked folded position. It is clear that a pinor stud on a leg member could serve the same function as the lip 27.

By positioning the latching mec'hanism so that it is adjacent the middleportion of each of the leg members, the shock of rapid engagementbetween the hook member 25 and the 'lip 27 is materially reduced. If theleg members are moved toward folded position at |a uniform angularVelocity, it is clear that the lower portions of each leg member travelat a greater linear Velocity than the upper portions do. Since the legmembers are normally pulled shut rapidly by upward movement of the uppercollar 10, the location of the l'atching mechauism and the accompanyngreduction in shock is important.

As best seen in Fig. 2, when the leg unit is in locked folded position,each bracing link 14 is inclined outwardly at a slight angle from thestandard 11. rThis factor is important in disengaging the leg unit topennit it to move to its outwardly spread position. Since the entire legunit is mounted for limited slidable movement relative to the standard11, downward pressure on the finger portion 26 moves the upper collar 10and the lower collar 16 downwardly against the upward force of thecompression spring 23, and removes the lip 27 from the notch 25a in thehook member 25. Because of the slight angle in the bracing link 14, thedownward force on the finger portion26 transmits a component of forcetothe upper end of the bracing link 14 in a direction outwardly of thestandard 11 which assists in the initial movement of each leg member 8toward its spread position.

It is desirable that the leg unit be frictionally balanced so that thetop collar will Continue to move downwardly slowly under the force ofgravity until it comes to rest on the top surface 29 of the stationarymember 24. In this position the leg members are in their outermostspread position.

The foregoing detailed description is given for clearness ofunderstanding only and no unnecessary limitations should be understoodtherefrom, for some modifications will be obvious to those skilled inthe art.

I claim:

1. A portable stand comprising: an upright tubular standard; a leg unitincluding an upper collar slidable' on the standard, a plurality of legmembers hinged to said upper collar for movement from an outwardlyspread position to a folded position adjacent the standard, and a lowercollar mounted on the standard for a limited slidable movementlongitudinally of the standard; a compression spring in said standardbearing between the lower end of said standard and a portion of saidlower collar to yieldingly maintain said lower collar in its uppermostposition on the standard; stationary hook members secured to saidstandard, each of said members having a downwardly open notch; andbracing links joining said lower collar to each of said legs and beingmovable with the leg members to folded position adjacent the standard,each of said links having a narrow upper lip positioned to snap into acorresponding notch in one of said book members when the leg members aremoved to folded position, and each of said links in folded positionbeing inclined upwardly and outwardly of the standard whereby a downwardforce on said leg unit compresses the spring disengaging each of thesaid lips from its corresponding notch and pivoting each of the linksoutwardly of the standard to move the leg members to their spreadposition.

2. A portable stand, comprising: anupright standard; a leg unit having.a plurality of legs and bracing links hinged for movement from anoutwardly extended position to a folded position adjacent the standard,said leg unit being mounted slidably on the standard for a limitedmovement longitudinally thereof, each of the bracing links 4 havingupperl and lower end portions pivotally secured to one of the legs andto the standard, the upper end portion being outwardly inclined fromsaid standard when in folded position; aV stationary portion on thestandard positioned adjacent said leg unit; a latching portion on theleg unit positioned for cooperative locking engagement with saidstationary portion when said legs are moved to folded position; andspring means yieldably urging said entire leg unit longitudinally of thestandard to maintain said latching portionand stationary portion inlocking engagement when the legs are in folded position, said legs beingunlocked from folded position by moving the entire leg unitlongitudinally of the standard against the action of said spring meansto disengage said latching portion from said stationary portion and tourge the upper end portion of each of the bracing links outwardly of thestandard to move the leg unit to its outwardly extended position.

3. A portable stand, comprising: an upright standard; an upper and alower collar each slidably secured on the standard, the lower collarbeing secured by a pin in slot connection to provide limited movementlongitudinally of the standard; spring means normally urging the lowercollar in the direction of said stationary latching portion; a leg unithaving a plurality of leg members hinged to the upper collar formovement from an outwardl'y spread position to a folded positionadjacent the standard, said leg unit including braeing links each havingupper and lower end portions pivotally secured to one of the leg membersand to the lower collar respectively, the upper end portion beingoutwardly inclined from the standard when in folded positionyastationary latching portion secured to said standard and positionedadjacent said leg unit; and a cooperating latching portion on the legunit positioned to yieldingly engage said stationary latching portionand lock the leg members in folded position when swung adjacent thestandard, downward movement of the leg unit disengaging said cooperatinglatching portion and urging the upper end portions of each of thebracing links outwardly of the standard to move the leg members tosupporting position.

References Cited in the file of this patent UNITED STATES PATENTS703,873 Whetham July 1, 1902 1,258,5l8 Ankovitz Mar. 5, 1918 1,364,169Wolff Jan. 4, 1921 2,549,584 Eller Apr. 17, 1951 hen..

